Most digital cameras today are similar in size to and behave like conventional point-and-shoot cameras. Unlike conventional cameras, however, most digital cameras store digital images in an internal flash memory or on external memory cards. Some digital cameras are also equipped with a liquid-crystal display (LCD) or other type of display screen on the back of the camera. Through the use of the LCD, most digital cameras operate in two modes, record and play, although some cameras only have a record mode. In record mode, the LCD is used as a viewfinder in which the user may view an object or scene before taking a picture. In play mode, the LCD is used a playback screen for allowing the user to review previously captured images either individually or in arrays of four, nine, or sixteen images.
Besides the LCD, digital camera user interfaces also include a number of buttons or switches for setting the camera into one of the two modes and for navigating between images in play mode. Representative cameras of this type are the QV series by Casio Inc., of Dover, N.J. The QV series typically includes two navigation buttons labeled "-" and "+", a mode button, a display button, a zoom button and a delete button. Play mode for a QV camera begins with a default screen displaying a full-sized individual image. Other images stored in the camera may then be displayed in a backward or forward sequence by pressing the "-" and "+"navigation buttons, respectively. Pressing the "mode" button during play mode causes four images to be displayed on the LCD in a 2.times.2 array, and pressing the "mode" button again causes nine images to be displayed in a 3.times.3 array. The user can then "page" through screens of image arrays by pressing the navigation buttons, or the user can move from image to image in the arrays by first pressing the display button and then traversing across the images in the rows of the arrays using the navigation buttons. The user may have the full-sized image displayed of a chosen image by pressing a "zoom" button or can delete the image by pressing a "delete" button. When the camera is operating in play mode and the user wants to capture an image, the user must first return the camera to record mode by pressing the "mode" button again.
The DSC-F1 digital camera by Sony Electronics Inc., San Jose, Calif., has a more complicated user interface and method for changing operating modes. FIG. 1A is a right-rear view of the DSC-F1, and FIG. 1B is a left-rear view of the DSC-F1. The DSC-F1 includes a Power/Function dial 12 for switching between play and record mode, and a Menu/Execute jog dial 14 for displaying menus and selecting items. The user can change from record mode to play mode by pressing a lock button 13 in the center of the dial 14 while rotating the Power/Function dial 12 to the "Play" setting. Once in play mode, the user and may then scroll through full-sized images on the display using the scroll buttons 16. Most camera functions are controlled through menu screens, which are accessed through either the Power/Function dial 12 or the Menu/Execute jog dial 14.
One disadvantage of two mode digital cameras, such as the ones described above, is that since the cameras only have two modes, many of the camera features must be accessed through multiple levels of menus and/or navigation screens, which is inconvenient for the user. For instance, in the DSC-F1, play mode functions are controlled through a play menu, which is accessed by pressing the Menu/Execute jog dial 14, as shown in FIG. 1B. Once a list of menu items is displayed, the user can turn the Menu/Execute jog dial 14 to move a cursor up and down the list. Pressing the Menu/Execute jog dial 14 while the cursor is over a selected function then executes that function. One function that may be selected is a search function, which displays nine images on the display in a 3.times.3 array and allows the user to scroll backwards and forwards through the images by turning the Menu/Execute jog dial 14 accordingly.
Like the digital cameras described above, most digital cameras suffer the disadvantage of forcing the user to change the operating mode of the camera from play mode to record mode before being able to capture another image. In cameras such as DSC-F1, this can be a cumbersome event, since the user must press the lock button 13 while simultaneously rotating the Power/Function dial 12 to the proper setting. Assuming the image the user wanted to capture was fleeting, by the time the user located the Power/Function dial 12, pressed the lock button 13, and rotated the dial 12, the object the user wanted to capture may have passed.
One way to make the camera user interface less cumbersome and to simplify the method of changing operating modes is to provide additional hardware buttons on the camera interface which correspond to each mode. But as seen in FIGS. 1A and 1B, adding too many buttons to the user interface may complicate the operability of the camera since it forces the user to memorize too many button functions and/or key sequences. Another disadvantage of adding too many buttons to the user interface is that each additional button increases the overall cost of the camera.
What is needed therefore, is an improved method and apparatus for changing the operating modes of an image capture device. The present invention addresses such a need.